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Copy of AP Bio- Evolution 1: Introduction to Evolution
Transcript of Copy of AP Bio- Evolution 1: Introduction to Evolution
Evolution: An Introduction
Science Does Not Happen In A Vaccuum
Darwin didn't freestyle Evolution from nothing.
Thinking about life was pretty standard scientific fare for the 19th century.
Had life always existed as it does now? Was it always changing?
How old was the Earth (Bible: ~7,ooo years old).
What's up with all these fossils?
Rock takes a long time to form!
The processes happening on Earth
now are similar to those that happened
in the past
What's the deal with that?
Why don't organisms stick around?
Populations would like to grow forever, but....
Jean Baptiste Lamarck
1. Life Evolves!
2. Inheritance of
3. Use and Disuse!
(Only the first bit is right, just ask this guy!)
How come I don't see any trilobites at the beach?
Bonsai Tree Babies are Regular Size
Compared to what actually goes on, this seems quaint!
This Was The Thought Stew That Darwin Worked In!
Darwin: Brief Biography
A remarkably unspectacular young life.
Comfortable family wealth.
Notoriously undecided about a job; Medschool, Parsonage, Naturalist... Whatever....
Family connections got him a gig as the captains companion on the
Circumnavigation of the globe!
5 years (22-27)!
Read, Collected, Wrote & Thought!
The Galapagos Islands
An important stop for Darwin.
Weird, unique animals.
The "A-ha!" Moment:
"The natural history of these islands is eminently curious, and well deserves attention. Most of the organic productions are aboriginal creations, found nowhere else; there is even a difference between the inhabitants of the different islands; yet all show a marked relationship with those of America, though separated from that continent by an open space of ocean, between 500 and 600 miles in width. ...Hence, both in space and time, we seem to be brought somewhere near to that great fact—that mystery of mysteries—the first appearance of new beings on this earth."
There are 12 species of Galapagos Finch.
Different beak structure driven by different feeding behavior.
All share a common immigrant finch ancestor
The only example of natural selection in the "
Origin of Species
All 1 species.
Different shell shapes due to different cactus plants on different islands.
The only swimming lizard in the world!
-spiky dorsal fins
-feed exclusively on
-expel salt from their
Darwin came home....
...published his journal...
...married his cousin...
...had four children...
...buried one of them...
...did a lot of other work...
...and didn't publish his theory FOR 20 YEARS!
He recieved a paper from a young naturalist asking for his thoughts on a new theory.
The same theory he had developed 20 years earlier.
He wrote a quick paper.
Both papers were published simultaneously.
And Darwin wrote a book.
Probably the most important one ever on Biology.
Introducing a whole new idea about how life evolves
Alfred Russel Wallace
(1809 - 1892)
How it Works:
Common Ancestry of Life:
among individuals (observation)
for Limited Resources (inference)
4. Successful competitors survive, reproduce, & pass on their traits (observation)
of Offspring (Malthus)
5. Repeat 1-4 every generation over millions of years (Lyell)...
...& life will
to the environment .
Reaction to the Theory
Competition for limited resources!
About those finches...
Most Babies won't grow up!
No two are quite the same!
It's the "Struggle for Existence!"
The selective pressure of the Galapagos Environment has driven the evolution of the finches.
Beaks are very important for birds.
The environment determines fitness!
Any birds that survive pass on their beak traits to their offspring.
Repeat for millions of years.
Darwin provided a lot of examples of "
Just like natural selection, but "fitness" is determined by human needs/wants.
Big changes can happen very fast.
Life will always adapt if it can.
Spraying of pesticides kills all of the pests who aren't resistant.
The resistant survivors reproduce...
...resistance increases (leading to more spraying, more resistance...)
Similar mechanisms drive the evolution of:
antibiotic resistance in bacteria
antiviral resistance in viruses (HIV)
150 years later, we have a mountain of examples of natural selection in action.
In the modern age, the focus has been on quantifying the effects of natural selection on the characteristics of a population.
Take home message: Natural Selection is universal!
A fundamental conclusion of
If we accept that life evolves, logic suggests that all of
life should share a common ancestor.
This is supported by evidence.
The pattern of evolution of life on Earth.
Public reaction was mixed.
Certain religious perspectives can't reconcile evolution with their modes of thinking.
Scientifically, Evolution is the unifying principle of all other fields of Biological study.
Natural selection (and other modes of evolution) are as close to biological "laws" as anything going.
"Nothing in Biology makes sense except in the light of evolution"
Issues with evolution are most often due to misunderstandings about the Theory:
“if we came from apes how come were not hairy and have a big mouth and did we end up looking like we do know and besides there isnt any serious proof of apes they showd a video saying an ape was wondering around in the forest that thing looked exactly like a costume that i had saw at a store know one ever cought an ape”
-From a post on the internet
2 facts, both explained by common ancestry:
Similarity in skeleton's of 5 great Ape species
Similarity between fossils and modern organisms
The only illustration in "Origin" 1st ed:
Another tree by Ernst Haekel
A modern tree (informed by DNA analysis):
The ultimate tree (DNA again)
What did people think about life on Earth 200 years ago?
How do organisms evolve?
Explain the development of evolutionary theory, the contributions of the people discussed in this presentation, and the evidence that they based their contributions on.
Describe the process of natural selection and give at least three examples of how it can lead to changes in a species.
Compare natural selection with artificial selection.